Thin-film devices covered by the present invention include a magneto-resistive effect element (hereinafter referred to as “MR element”), a variety of semiconductor elements and a circuit element such as an inductor. Among them, the MR element is used not only as a magnetic detecting element or a magnetic memory but also as a reproducing element for a thin-film magnetic head. The inductor forms an independent circuit element by itself and is also used as a recording element for a thin-film magnetic head.
In thin-film devices of this type, since the signal frequency has been increased for higher speed and performance, the ensuing increase in loss and heat generation due to the skin effect that a signal current flows at the surface of a lead conductor film in a concentrated manner has become a problem. As a measure against the skin effect in association with the increased frequency, for example, Japanese Unexamined Patent Application Publication No. 1106-302640 discloses a bonding wire, while Japanese Unexamined Patent Application Publication No. 2000-48315 discloses an inductive element.
In thin-film devices of this type, however, there is generally adopted a structure in which a thin-film element and a lead conductor film are embedded in an insulating film, and such a structure requires a system through which heat generated at the lead conductor film by the skin effect in association with the increased signal frequency can be conducted out of the insulating film for radiation of heat, so that it is difficult to efficiently radiate heat.
If it is possible to increase the sectional area of the lead conductor film, the surface area will also increase accordingly, relieving the problem due to the skin effect, but since further miniaturization of the lead conductor film and the thin-film element is required for miniaturization of the thin-film device, as well as for higher speed and performance, the above measures cannot be adopted.